Compressor starting pressure relieving attachment



Oct; 27, 1953 G. F. PFEIFER 2,656,970

COMPRESSOR STARTING PRESSURE RELIEVING ATTACHMENT Filed Sept. 16, 1949 5 Sheets-Sheet l I V I i 75 75 L a 78 73 7 l v i /2 /3 4T8 J A H3 IN VEN TOR. 4790)?76 fiF/ei/er ATTD RN EYS Oct. 27, 1953 PFElFER 2,656,970

COMPRESSOR STARTING PRESSURE RELIEVING ATTACHMENT Filed Sept. 16, 1949 5 Sheets-Sheet 2 IN VEN TOR.

ATTEIRN EYE Oct. 27, 1953 G. F. PFEIFER 2,656,970

COMPRESSOR STARTING PRESSURE RELIEVING ATTACHMENT Filed Sept. 16, 1949 3 Sheets-Sheet 3 pil 7 za l v.32 J

' /5 A 9 4 w 85 i W 97 as INVENTOR. s/

2 T 87 (ea/"9e P/ez'zer 84 ATTDRJN EYs Patented Oct. 27, 1953 COMPRESSOR STARTING PRESSURE RELIEVING ATTACHMENT George F. Pfeifer, Quincy, Ill., assignor to Quincy Compressor Company, Quincy, III., a corporation of Illinois Application September 16, 1949, Serial No. 116,150

9 Claims. 1

This invention relates to improvements in air compressors and particularly devices for facilitating starting compressors, and in particular the invention includes instrumentalities incorporated in a compressor for relieving the pressure, or unloading, or withholding the load in starting and until the compressor reaches normal operating speed.

The purpose of this invention is to provide means for automatically unloading a compressor in starting so that the operating parts may reach the usual operative speed before work is performed thereby.

In the usual type of air compressor, or the like, the valve of the cylinder head starts functioning as soon as the crank shaft turns over and this places a load on the starting elements which delays the starting operation of the compressor. With this thought in mind this invention contemplates means operated by a lubricating oil pump of a compressor which holds the intake valve of the compressor cylinder open until the compressor reaches the normal operating speed.

The object of this invention is, therefore, to

provide fluid pressure operated means controlled by the lubricating oil of a compressor for holding the compressor unloaded until it reaches full speed in which the elements may be incorporated in the compressor unit.

Another object of the invention is to provide unloading mechanism which will permit a lag or definite delay of the escape of the operating air so that the compressor is held unloaded for a short time after reaching full speed.

Another object is to provide unloading mechanism which will permit an instantaneous action of the fluid pressure controlling valve when the pressure reaches a predetermined point at which the motor is automatically stopped to permit the compressor to come to a free unloaded rolling stop.

A further object is to provide unloading mechanism which may be applied to two-stage as well as single-stage compressors, and when used on two-stage compressors will simultaneously hold the high pressure intake valve open and at the same time vent the intercooler which connects the discharge of the low pressure cylinder to the high pressure intake, to the atmosphere so that a one hundred per cent unloading is effected.

A still further object of the invention i to provide means incorporated in a compressor for holding the cylinder valve or valves open in starting the compressor whereby the pressure in the cylinder is relieved until the compressor reaches full speed in which the attachments and parts associated therewith are of simple and economical construction.

With these and other objects and advantages in view the invention embodies a diaphragm actuated plunger for holding the check valve of the compressor cylinder open as the compressor is started, and a valve actuated by the lubricating oil pump of the compressor for admitting pressure to an opening above the diaphragm in starting and until the compressor reaches full speed.

Other features and advantages of the invention will appear from the following description taken in connection with the drawings wherein:

Figure 1 is an end elevational view illustrating the relative positions of the oil actuated valve and diaphragm actuated plunger with the connection from the valve to the plunger housing.

Figure 2 is a longitudinal section through an end of a compressor with parts broken away, taken on line 2-2 of Figure 1 and showing the end of the crank shaft and fluid actuated valve.

Figure 3 is a vertical section taken on line 3--3 of Figure 1 illustrating the diaphragm controlled check valve of the compressor and with parts broken away.

Figure 4 is a vertical section similar to that of Figure 2 showing the air pressure actuated valve in elevation and with parts of the compressor broken away.

Figure 5 is a detail showing a sectional plan through the fluid pressure actuated valve and taken on line 5-5 of Figure 4.

Figure 6 is a detail showing a vertical longitudinal section through the oil pressure relief valve.

Figure 7 is a detail showing a section through the upper part of a compressor cylinder illustrating a modification wherein the diaphragm is replaced by a spring loaded piston.

Figure 8 is a detail showing the upper end of the compressor with the lower part broken away and showing the arrangement of the low and high pressure cylinders.

Referring now to the drawings wherein like reference characters denote corresponding parts the automatically operated compressor has a crank case It with a crank shaft II, a low pressure cylinder [2 a high pressure cylinder I3, and intercooler I4 through which the discharge of the low pressure cylinder is connected to the intake of the high pressure cylinder, an oil pump l5 actuated by the crank shaft, an oil pressure actuated control valve 16, and an intake valve I! that is actuated by a diaphragm I8 through a plunger IS.

The crank case I0 is of usual construction and the crank shaft II is journaled therein with the usual bearings. The low and high pressure cylinders I2 and I3, respectively are bolted to the crank case and the oil pump I5 which is psitioned in the crank case is actuated by a cam suriace 2d on the crank shaft with a connection from'the oil pump to the oil actuated control valve.

The oil pump I5 is provided with a plunger 2! that engages the cam surface 20 of the crank shaft and this plunger is mounted in a cylinder 22 with valves 23 and 24 in the lowerend of the cylinder, and the pump is provided with a strainer 25 which is carried by the lower end of the cylinder.

Lubricating oil is pumped from the oil pump l5 through a pipe 26 to a passage 21 in the crank case head 28 in the usual manner and the fluid pressure controlled valve I6 is positioned in a cap 29 on the end of a control valve cylinder 3G formed in an enlargement of the head 28, as illustrated in Figure 2. A supplementary passage 3I is provided throughwhich the oil passes to the cylinder 30.

A piston 32 is positioned in the cylinder 36 and resiliently held against the oil pressure by a spring 33. The piston 32 is provided with a centrally disposed hub 34 in which an inner cup shaped piston 35 is positioned in a cylindrical opening therein The inner piston 35' is retained in the hub by an annular ring 36 which limits the outward movement of the piston 35 and a spring 3'! is provided in the piston 35 to urge the piston outwardly against a plunger 38 in a bushing 39. which isthreaded into a valve opening 40 in the cap 29. The plunger 38 is positioned to hold the valve I6 against a seat 4| in the cap which,- as illustrated in Figure 5 closes-a compressed air passage 42 through which compressed air is suppliedfrom a tube 43 through a tube-44 to the upper side of the diaphragm I8, the tube 44 being connected to a head 45 by which the diaphragm is clamped against a valve casing 46, through a fitting 4-1, as illustrated in Figure 3.

The inner end of'the valve I6 is provided with a packing washer 48 that engages the correspondin'g end of the bushing 39 and provides a seal preventing the compressed air passing into the lubricating system.

The outer end ofthe cylinder 3!] is provided with a return passage 3 through which oil leaking by the piston 32- passes back to the crank case and the bushing 39 is provided with alaterally disposed vent opening 9 through which air is released from the diaphragm valve.

The crank shaft II is provided with the usual lubricant passages 49 and a centrifugally actuated relief valve is provided in an extension formed by the counterbalance weight Silwith the valve formed by a plunger 5| having a valve surface 52 on the outer end that is positioned to seat against the inner end of a bushing 53, as shown in Figure 2, and the plunger is resiliently held inward by a spring 54. This valve is closed by centrifugal force after reaching a predetermined speed and by the pressure of the lubricating oil so that in starting and after a predetermined speed isreached the pressure builds up in the oil sufiiciently-to actuate the' piston 32 to close valve Iii while the compressor is in operation and when the compressor is inoperativeorthe speed falls to a predetermined point the spring 54 opens the valve 5| to relieve the pressure so 4 that compressed air may be admitted to the diaphragm.

The diaphragm I8 is secured between flanges of the valve casing 46 and head 45 by screws 55 and, as shown in Figure 3 the under side of the diaphragm contacts a head 56 of a plunger 51 and the plunger extends downwardly through the valve casing with the stem I9 thereof positioned to engage the valve I"I so that as the diaphragm is bowed downwardly by air pressure in the head 45 the valve I1 is held away from the seat 58 and the intake valve of the high pressure cylinder I3 is consequently held open and as it cannot close air is not compressed in the cylinder, and as the pressure is thereby relieved the cylinder is unloaded.

A spring 59 is provided in a bushing 69 in the lower end of the valve chamber 6| in the head 62 of the compressor and thi spring normally holds the valve I'I closed on the compression stroke of the piston in the compressor.

The plunger 5'? is also provided with a packing washer 63 in an annular cup shape section 64 and this washer is held against a valve seat 65 by a spring 66, thereby providing a valve for preventing the escape of air from the low pressure cylinder when the compressor is operating. By the same means, however, the diaphragm I8 holds'the plunger 5! and the ring 63 downwardly to open this valve at thesame time the valve I? is opened whereby air from the low pressure cylinder enters the inner cage 61, through which the plunger 5i passes, through openings 68, passages 69, through the valve formed by the ring 63 and to the atmosphere through openings 10. The cage 67 is held in the compressor head 62 by sleeve II that is threaded in the pressure head and the valve casing 45 is threaded on the upper end of the sleeve.

With the part arranged in this manner the oil pressure of the compressor will be'negligible when the compressor is inoperative and until it reaches a predetermined speed and with the pressure relieved from the end of the piston 32 of thevalve it the spring 33" will hold the piston inwardly so that the valvewill open, and air pressure will be supplied to the diaphragm I8 sothat the valve I7 and 63 thereon will be held open, and with the ends of the cylinders i of the compressor open to the atmosphere'pressure will not build up in the cylinder and the cylinders will be unloaded.

The elongated annular recess i2 is provided for conditions of pulsations in the lubricating system, and with the construction indicated the piston 32 can fluctuate with the pulsations, but cup shaped piston 35 will remain in contact with plunger 38 and hold valve I5 onto its seat during pulsations. If piston 32 were solid, with each pulsation the stem 38 would move back and forth, permitting valve I6 to alternately seat and'unseat.

The lubricating system of the compressor is provided with an oil pressurecontrol valve formed with aball 13in an opening 74 which is'in communication with the oil passage 2! in the head 28 and as oil' entering the valve through a port I5forces the ball away from a seat IS the oil circulates through the valve passing back into thecrank case through an opening IT. The ball is-held against the seat by a spring i8 and the tension of the spring is' adjusted by an adjusting nut I9 that is threaded into the tubular section of the valve casing andthe head of the adjusting screw is provided with a packing ring 8| that coacts with a surrounding sleeve 82 to prevent oil leaking through the valve.

A modification is illustrated in Figure 7 wherein the diaphragm controlled valves, shown in Figure 3, are replaced by a spring loaded piston 83 in a cylinder 84 formed in a bushing 85 to which a tube 85, similar to the tube 44, is connected by a fitting 81. The piston 83 is provided with a plunger 88 having a conical shaped valve surface 89 thereon and the opposite end of the plunger is provided with a small cylindrical section 98 in which a spring 9| in a recess 92 of the compressor cylinder 93 extends. The spring 9I holds the valve surface 89 against a seat 94 of a valve bushing 95 whereby air passes from a recess 95 communicating with the low and high pressure cylinders, through a passage 91, to the valve, and holds the valve closed with the cylinders of the compressor functioning in the usual manner. When the compressor is inoperative or rotating at slow speed air pressure is admitted to the tube 86 by the valve I6 and the pressure acting against the piston 83 holds the valve open, similar to the operation of the valves I! and 63 whereby the compressor cylinders are unloaded until the compressor reaches normal speed.

With the parts arranged as disclosed and described a compressor is unloaded and is relieved of performing work whereby the pistons may slide back and forth in the cylinders until the crank shaft reaches normal speed and when the speed desired is obtained a valve including the valve member 5| is urged, by centrifugal force, against the valve seat 52 whereby pressure is built up by the pump l5 in the lubricating passages and this pressure actuates the piston 32 whereby the piston travels outwardly against the stem of the valve I6 thereby closing the compressed air connection to the tube 44. Air trapped in the tube 44 escapes around the valve stem 38 and passes through a laterally disposed passage 3 and to the interior of the crank case through the connection 3.

The compressor unloading system of this invention, therefore, includes a pair of valve units, each including a plurality of valve elements and the control valve, as illustrated in Fig. 2 is retained in the open position with the valve member It separated from the seat 4| by the compressed air connections from the tube 43 to the valve casing 46 and the intake valve through the tube 44 is open so that the intake valve is retained in the open position until centrifugal force resulting from the speed of the crank shaft draws the valve member 5| against the seat 52, at which time pressure builds up in the lubricating passages, forcing the valve 32 against the valve stem or plunger 38 whereby the valve I6 is closed against the seat 4! and the pressure on the upper side of the diaphragm I8 is relieved.

With the pressure acting against the upper side of the diaphragm I8, the diaphragm moves downwardly urging the stem 5'! and valve stem I9 downwardly whereby the valve I1 is opened and a continuous air passage is provided from the interior of the cylinder of the compressor through the valve casing and to the atmosphere through the opening I0, the valve 63 also being separated from the seat 65. As the compressor stops the pressure from the lubricating pump is relieved and the spring 33 moves the piston 32 away from the plunger 38 whereby the air pressure in the tube 43 drives the valve I6 away from the seat so that the air pressure is again applied to the upper side of the diaphragm I8 and the intake valve opened to the atmosphere, thereby unloading the compressor to facilitate stopping of the rotating parts thereof.

It does not require a long time for the oil pressure to build up sufficiently to overcome piston 32 and spring 33 and to prevent the load coming on the motor too suddenly, the stem 38 in seat cap 39 is a close fit and thereby restricts the flow of air from the diaphragm valve assembly, thereby holding the compressor unloaded for a short time even after the motor has come to full speed.

It will be understood that other modifications may be made in the design and arrangement of the parts without departing from the spirit of the invention.

What is claimed is:

1. In a compressor, the combination which comprises a compressor block having a cylinder therein, a crank shaft journaled in said block, a piston in said cylinder connected by a connecting rod to said crank shaft, said crank shaft having a cylindrical extension providing a counterbalancing weight thereon and said cylindrical extension having a cylinder with a valve seat in the outer end thereof therein, a valve in said cylindrical extension positioned to coact with said valve seat upon rotation of said crank shaft, means resiliently urging said valve away from said valve seat, a lubricating pump actuated by said crank shaft, an intake valve in the cylinder of the compressor block, a compressed air connection extended from said intake valve for retaining said intake valve in an open position in which said compressor is unloaded by compressed air from said connection, a control valve in said compressed air connection, and means applying pressure from said lubricating pump to said control valve for retaining said control valve in the position of closing the compressed air connection, the valve in said cylindrical extension of the crank shaft positioned to remain in the open position to relieve pressure on said control valve with the crank shaft turning slowly and adapted to be closed by centrifugal force to apply pressure of the lubricating pump to said control valve to close the compressed air connection whereby the intake valve of the compressor cylinder is relieved and the valve is adapted to close to permit the compressor to function.

2. A compressor as described in claim 1 wherein bleeder passages are provided through said control valves for providing escape of air through said control valves for providing escape of air trapped in the connection from the control valve to the intake valve.

3. A compressor as described in claim 1 wherein said intake valve is provided with a valve casing having a diaphragm therein and the diaphragm is positioned whereby pressure on the outer surface thereof causes the diaphragm to actuate a valve stem that opens said intake valve to the atmosphere.

4. In a compressor, the combination which comprises a compressor block having a cylinder therein, a crank shaft journaled in said block, a piston in said cylinder connected by a connecting rod to said crank shaft, a lubricating pump actuated by said crank shaft, an intake valve in the cylinder of the compressor block, a compressed air connection extended from the said intake valve for retaining said valve in an open position, a control valve in said compressed air connection, said control valve positioned to coact with a valve seat in a control valve cylinder of said compressor block, a piston in said cylinder, means applying pressure from said lubricating 'pump to said piston to actuate the piston for retaining the valve against said valve seat, resilient means in said control valve cylinder for urging the piston in said cylinder away from the control valve, a bushing having a bleeder opening therethrough positioned in the control valve cylinder and providing a guide for said control valve and means applying pressure from said lubricating pump to said control valve for retaining said control valve in the position of closing the compressed air connection to the intake valve, said means positioned to relieve pressure in said control valve with the crank shaft turning slowly and adapted to be actuated by centrifugal force to apply pressure from said lubricating pump to said control valve to close said compressed air connection whereby pressure to the intake valve is relieved and the compressor adapted to function.

5. A compressor as described in claim 4 wherein the intake valve is provided with an extended valve casing and the valve is actuated by a diaphragm extended across said casing, and wherein said compressed air connection extends to the outer end of said valve casing.

6. A compressor as described in claim 4 wherein the pressure of the lubricating pump is controlled by a valve carried by the crank shaft and actuated by centrifugal force.

'7. In a compressor, the combination which comprises a compressor block having a cylinder therein, a crank shaft journaled in said block, a piston in said cylinder connected by a connecting rod to said crank shaft, a lubricating pump actuated by said crank shaft, an intake valve in the cylinder of said compressor block, a valve casing extended from said intake valve and aligned therewith, a diaphragm extended across said valve casing, a slidably mounted valve stem extended from said valve casing to said intake valve and positioned to open the intake valve upon application of pressure to said diaphragm, resilient 'means for retaining said intake valve closed, a

compressed air connection extended from the outer end of said valve casing, resilient means for retaining said intake valve in a closed position in which said compressor is unloaded, a control valve having a stem extended therefrom positioned in said compressed air connection, means applying pressure from said lubricating pump to said control valve for retaining said control valve in the position of closing the compressed air connection, and means positioned to relieve pressure on said control valve with the crank shaft turning slowly and adapted to be actuated by centrifugal force to apply pressure of the lubricating, pump to said valve to close the compressed air connection whereby the intake valve of the compressor cylinder is relieved and the valve is adapted to close to permit the compressor to function.

8. A compressor as described in claim '7 wherein a valve casing extended from said intake valve is provided with openings to the atmosphere and a valve for closing said openings when pressure on the diaphragm in the casing is relieved.

9. A compressor as described in claim '7 wherein the means for applying pressure from the lubricating pump to the control valve comprises a valve incorporated in said crank shaft and actuated by centrifugal force resulting from rotation of the crank shaft.

GEORGE F. PFEIFER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,606,060 Cox Nov. 9, 1926 1,765,289 Steenstrup June 17, 1930 2,047,489 Pfeifer July 14, 1936 2,115,546 Aikman Apr. 26, 1938 2,199,486 Doeg May '7, 1940 FOREIGN PATENTS Number Country Date 205,306 Switzerland 1939 

